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What is the Flymo Mighti-Mo 300 Li?

The Mighti-Mo 300 Li is one of the smallest, lightest and most affordable cordless lawnmowers. Boasting a 30cm cutting width, five cutting heights and a 30-litre grass-collecting box, the removable battery should be good for up to 250m² – or one tennis court.

We managed around half that area at 125m² off a single charge, and found the small bin needs emptying frequently. Build quality is rather flimsy, so the lawnmower won’t cope well with rough ground or rugged handling. Nevertheless, the Mighti-Mo’s lightweight build, frill-free design and superb price make it a good choice for small garden lawns.

Related: Best cordless lawn mower

Front bottom view of a black Technics SL 1500C turntable kept on a white background

Flymo Mighti-Mo 300 Li – Design and features

Flymo’s Mighti-Mo 300 Li has been out for a while and, by all accounts from my local hardware store, it’s a best-seller. It’s small and light, but a big part of that appeal is undoubtedly the price. At the full £220 ticket price, it comes in well below most of the brand-name cordless mower competition, and it’s frequently discounted to well below that.

Out of its compact, colourful packaging, the Mighti-Mo 300 Li requires minimal assembly. That involves attaching the two-part metal handle and assembling the two halves of the plastic grass box. Two cable clips are supplied to keep the control cable from flapping around.

Close up view of black Audeze LCD 1 headphone's earcups laid on a black background

The upper half of the handle has two holes to choose from when assembling, raising the reach by about 30mm in the upper position. The handle does fold flat for storage, but that isn’t an overly easy task.

You need to loosen off both of the lower clamp wheels and the large orange wing nuts quite a long way before the handle folds. You also need to ensure the cutting-height lever is on the lowest setting, or it stops the handle going flat. Get all that sorted and the Mighti-Mo won’t take up much room in the shed at all.

Close jup view of a Swann day/night 4K Spotlight NVR camera mounted to a roof edge in a corner

The controls are typical of an electric mower, with a press-button lock-release on the centre cluster before the mower can be started with either of the orange grab-levers. This setup is so typical of a Flymo electric corded mower it still retains a mains cable clip on the cluster. You can’t have too many bespoke parts at this price, you know.

View from top of a black Technics SL 1500C turntable kept on a white background

On top of the mower’s body is a carry handle and clear plastic cover. The latter unclips rather unceremoniously and lifts up to reveal the battery slot and kill-switch key hole. Two keys are supplied, although if you don’t have errant small people about likely to go play-mowing, you can just leave it in place.

Top front view of a black Fine Element contemporary convector heater standing on floor

Inserting or removing the battery involves pushing the release button at the front with one hand while pulling out the battery with the other. Unfortunately, you need a third hand or the dexterity of an octopus to hold up the flap at the same time; it simply falls forward. To insert, the battery requires lining up with its seat in the mower and pushing firmly into place.

Screenshots from Fine Element stove heater's app about master bedroom heating for 30 minutes

Much better engineered is the five-position grass cut-height adjuster, running from 25mm to 65mm in 10mm increments. It’s one of the few parts of the Mighti-Mo that feels solid and is nicely sprung, so you don’t have to physically lift the mower to go higher. The machine itself is so light, at under 10kg all-in, you do need to hold the body while you adjust the lever to stop the mower simply rolling off.

Screenshots from Fine Element contemporary convector heater's app about master bedroom heating for 30 minutes

Flip the Mighti-Mo over and the 30cm traditional mower blade is bolted with a single nut, making it easy to remove for sharpening or cleaning. The cutter deck is lightweight, fairly thin-wall ABS plastic. This needs to be treated with some care to avoid breakages over rough ground or obstacles.

The four plastic wheels are fitted loosely to simple steel-wire axles, allowing them to wobble fairly alarmingly. That adds to the overall flimsy feel, and a sideways push on the handle sees everything flex. That translates to a rather vague feel in use. There’s no mulching plug option, but you could simply remove the grass box and allow the cover flap to seal the ejector hole. Not ideal, but it just about works to mulch shorter grass.

Front-top view of a black Fine Element stove heater standing on floor

The battery itself is a robust aluminium-cased brick with a push-button, three-segment charge indicator. It’s remarkably similar to the indicators found on Husqvarna’s batteries, presumably because Flymo is a ‘budget’ sub-brand of the Swedish giant. There’s no way of seeing this battery indicator in use, however, so best ensure it’s fully charged before commencing mowing.

The dock-style charger has a front LED that glows red for standby, flashing-green for charging, and solid green for fully charged. It’s an intelligent charger so you can leave the battery docked and plugged in between mows, ensuring it will always be in tip-top condition when you come to use.

Well, that’s the theory. Sadly, our first Mighti-Mo battery/charger combination was faulty and didn’t charge at all. The replacement unit functioned perfectly.

A brown-silver Meaco Heat Motion Eye heater standing on a table beside a couchBlack Audeze LCD 1 headphones floating on a white background

Related: Best grass trimmer

Flymo Mighti-Mo 300 Li – Batteries, charging and run-time

The Mighti-Mo’s chunky battery looks fairly low capacity at 2Ah, but you do need to factor in the 40V operating system. That means the battery can deliver a respectable 80Wh of power. For comparison, you’d need a battery of almost 4.5Ah capacity to deliver the same total power in an 18V system.

The charger dock requires a little bit of jiggling of the battery and lining-up of pins to get the battery to lock into the holder. Unusually, there was no specification label of the charger, so there was no way to determine the rated charging output. It does charge a flat battery to full in around 1hr 50mins to 2hrs, which is respectably prompt, if not super-speedy.

A black and a white Analogue Pocket kept on a white and black background

Run-time will depend a little on the length, type and dampness of the grass you’re mowing. A light trim over a bone-dry bowling green will see the Mighty-Mo go on for a lot longer, and cover more ground, on a single charge. Early season long grass on a damp morning, far less.

On our mid-length mix of lawn and the usual weeds such as clover, we got a solid 21 minutes of mowing. That wasn’t 21 minutes constantly, because we had to stop mowing (and pause the stopwatch) while we emptied the bin. Since that was 10 times during the 21-minute long test, you can see the Mighti-Mo both collects effectively and has an annoyingly small bin.

Top side view of a brown-silver Meaco Heat Motion Eye heater standing on floor with control buttons on top

The result of the 21-minute run-time was a successfully mowed area of around 125m² of lawn. That’s exactly half of Flymo’s claimed 250m² area. Shorter, dryer grass and a flatter, less complex lawn area would certainly increase mowing coverage to get to Flymo’s figure.

If you want to extend your run-time and, hence, cutting area then you could, theoretically, buy a second battery direct from Flymo. At the time of this review, that will set you back £106.99 plus £8.99 postage. Since that’s approaching the price at which you can pick up the whole mower, the idea is a complete non-starter.

Close up view of burning wood and flames inside a black Fine Element stove heater

Flymo Mighti-Mo 300 Li – Handling and performance

Fully assembled, the Mighti-Mo 300 Li tipped our scales at just 10kg. That’s properly featherweight for a lawnmower of any power source, let alone one that carries its own battery on board. It’s commensurately small and compact, and its cute little form factor all but shouts out to owners of postage-stamp to pocket-handkerchief-sized lawns.

Set up, charged and ready to mow, the Mighti-Mo feels rather vague and wobbly. The wheels camber inwards a little and a test push suggested super-straight mowing lines are likely to be a challenge. The handle flexes and its connection to the mower feels like it’s attached with Blu Tack, even with the bottom clamp wheels tightened up hard.

On our first sample mower, the central switch cluster was very loose but we successfully tightened that with a screwdriver. The second sample was okay.

Right angled view of a black Fine Element contemporary convector heater standing on floor

The orange switch levers themselves aren’t great. When the release button is pushed in, the levers need pulling tightly into the handle. Release even the lightest amount of hand pressure on the levers and the mower stops. That takes a little getting used to, particularly when turning the mower or doubling back at the end of the lawn.

Get the hang of the levers and ignore the wobbling, though, and the Mighti-Mo isn’t a bad little mower. It’s fairly quiet when running, the cut-height adjuster is easy to use, and its ridiculously light weight makes is super-manoeuvrable around the lawn and incumbent obstacles. Subsequent tests by our octogenarian reviewer resulted in very positive feedback in this respect. She was  impressed with the ability to nip around the lawn and its ease of carrying in and out of the shed.

Front top view of a black Technics SL 1500C turntable kept on a white background

The highest 65mm setting is very high and might well be useful for early season cuts. Dropping down in 10mm increments is great; the 55mm topping longer grass and the 45mm creating an effective mow on our rougher lawn. The 35mm setting, combined with a curve on the test area, meant it went into full scalp mode for us. That also revealed the Mighti-Mo’s lack of, well, might. Get it bogged down in deep grass and the blade slows dramatically, actually stopping on the scalped line shown in the image.

A black Fine Element stove heater standing on floor

Backing up to the 45mm setting, cut performance is good if not the super-crisp look we’ve seen with more expensive mowers. Pickup is also respectable, as long as you don’t drop the deck too low to the ground. Do that and as much grass is dumped to the sides as gets collected. Leave it on a reasonable-height cut and the Mighti-Mo offers good grass pickup with few clippings left behind.

Close up view of rusty screws on a black Fine Element stove heater

That in itself highlights another issue, however; namely that compact bin. It isn’t large at 30 litres and the Mighti-Mo doesn’t pack enough punch to compress the collected cuttings. You’re going to be emptying the bin a lot, especially in the spring.

On our over-grown test lawn, we could barely manage two minutes of mowing before the box was full. There’s no indication of bin-full, either. The first you’ll know of it will be a trail of grass clippings on the lawn behind you.

Top side view of a brown-silver Meaco Heat Motion Eye heater standing on floor with control buttons on top

Unclipping the bin and carrying it is easy enough, but the narrow neck where it attaches to the mower makes it awkward to unload. Tip it up and the grass simply stays in the box. Nine out of ten times we needed to get a hand in the box to pull out the grass until it would flow out of the narrow opening.

Screenshots from Meaco heat Motion Eye heater's app about master bedroom heating for 30 minutes

Continuing on to mow the entire test area, we did get a reasonable 21 minutes mowing and trimmed down well over 100sqm of our over-grown lawn. As that would probably cater for more than 90% of UK garden lawns in one charge, you can see the market the Mighti-Mo is aimed at.

Flymo’s Mighti-Mo 300 Li just about passes muster as an ‘okay’ compact cordless lawnmower. If it cost the same as similar-spec peers we’ve tested – £300-£350 – then it would be crashing and burning to the bottom of the pile. Yet at around £200, or even much less, you just can’t ignore that value. None of its niggling issues are real deal-breakers, and if you have a small lawn and a tight budget, you really can’t go wrong with the Mighti-Mo.

Right angled view of a brown-silver Meaco Heat Motion Eye heater standing on white background

Why buy Flymo Mighti-Mo 300 Li?

Even at its full retail price, Flymo’s Mighti-Mo 300 Li isn’t a bad buy; and it’s frequently on special offer, which makes it even more appealing.

It’s lightly built, flimsy to use and has plenty of niggles – particularly the small, awkward to empty bin and lack of power in longer grass. Yet you can forgive it these grievances thanks to it being nippy, fairly effective on lawns realistically up to 150m², and very light to use and store. It won absolute top-marks from our octogenarian tester, even if it felt thoroughly out-gunned by the more affluent cordless machinery we’ve had on test lately.

A good buy on a tight budget? You bet.


The Mighti-Mo 300 Li isn’t perfect, but it remains a great value, super-light cordless mower for the smaller lawn.

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